The Bush Administration announced that it would review diesel sulfur and clean engine standards imposed by the Clinton-run EPA, postponing the regulation''s effective date for 60 days.

Speaking at her Senate confirmation hearing, newly-named EPA Administrator Christine Todd Whitman said she "has an obligation to review all the rules," issued by the agency under the Clinton Administration.

Trade groups representing oil refining and engine manufacturing companies are optimistic the review could lead to relaxed standards.

"We fully agree that there is a need for a Bush Administration review," said Mike Shanahan, spokesman for the American Petroleum Institute.

Under the rules, the amount of sulfur in diesel fuel would be drastically reduced by 97 percent in 2006, enabling new-generation diesel engines to run cleaner and meet established 2007 emissions standards.

EPA said the standards were justified to address the growing public health concern that particulate matter in diesel exhaust is a major cause of respiratory problems.